Heretofore, brominated compounds have been employed in thermoplastic polymers to make resins which have improved flame-retardance over the thermoplastic polymer alone. However, many such brominated compounds, such as decabromodiphenyl ether, tend to degrade these polymers at melt-processing temperatures, and to migrate in articles molded from the resin toward the surface of the molded article.
New brominated oligomers have now been discovered which when employed with thermoplastic polymers result in flame-retardant molding blends which have better stability toward thermal degradation than do resins which contain some known brominated flame-retardants. Moreover, the new oligomers do not exhibit any substantial tendency to migrate toward the surface of articles molded from the resins.